A novel design method for extending power back‐off range of broadband Doherty power amplifier

Abstract

In this article, a novel design method for extending the output back‐off (OBO) range of the Doherty power amplifier (DPA) is proposed. The influence of the power ratio of the peaking and carrier power amplifier on the bandwidth of the DPA is analyzed in detail. With the proposed theory, the simplified estimation of the bandwidth of the DPA for a specific OBO range can be carried out. A broadband high‐efficiency DPA working from 1.8 to 2.6 GHz (33% relative bandwidth) with 9 dB OBO level is designed to verify the proposed method. According to the measured results, the DPA achieves 44.6 to 46.8 dBm saturation output power and drain efficiency (DE) of 61% to 74%. And at 9 dB OBO level, the DE varies from 50% to 63% over the operation band. Furthermore, digital predistortion (DPD) measurement results show that the linearized DPA can meet the spectral requirements for modern wireless communication systems.